As is known, in the eyewear field, the so-called “flex” or elastic hinges are becoming widely used. These hinges in general are made of a female component, typically fixed to the front frame of the eyeglass, and a male component comprising a sliding guided carriage, in contrast to an elastic element, inside a housing placed on the temple of the eyeglass. The carriage element has one or more eyelets engaging with a hinge pin, which in turn is integral with the female component. An example of this hinge is disclosed in FR2741459.
For the operation of the hinge, the elastic contrast element of the sliding carriage, normally a coil spring, is constrained on one side to the bottom portion (the innermost one of the housing) of the carriage and, on the other, to abutting/stopping means which are integral in the longitudinal direction within the housing. These abutting means are configured in very different ways: generally, they are in the shape of screws or through pins, or in the shape of snap elastic components. The latter, also known as elastic holding clips, have the advantage of being able to be introduced into the housing, without providing holes or other visible changes to the outside of the housing, deforming elastically and then snapping in the desired working position in corresponding seats obtained inside the housing.
The elastic holding clips are highly appreciated, as they have a low aesthetic impact on the carriage housing (as opposed to screws or pins) and are very cheap and simple to manufacture. Snap elastic holding clips of the prior art, are disclosed in the same above-mentioned FR2741459, but also in EP1743207, EP2109795, WO2005/121873 being owned by the same Applicant and also WO2006/029776 and in some embodiments of WO2011/121554.
Also in the documents IT1420896 and EP2553519, it is proposed a very effective elastic hinge, provided with a fork carriage sliding in a rigid housing, wherein the holding clip of the carriage consists of a folded metal strip.
All these solutions have the advantage of being very simple to assemble but, by providing a snap engagement, they cannot be dismantled. In some cases—typically when a component breaks down—there is, however, the need to remove an elastic hinge, pulling the carriage out of its seat, so as to replace the malfunctioning components.
To meet this need, the known technique offers alternative solutions.
For example, this is obtained by using hinge versions wherein the carriage is constrained inside the housing by means of a screw, a pin or, more generally, a removable element. Examples of these solutions are disclosed in EP2009484, WO9739377, JPH11271691, EP0615149 and WO2011103949. As already seen above, the drawback of these solutions lies in the fact that the removable locking elements, such as screws or pins, are necessarily seen from the outside of the hinge, with consequent impact on the aesthetics of the hinge itself. Moreover, the locking element constitutes an additional component to be managed in the warehouse and to be handled in the assembly step, implying higher costs.
Alternative solutions, which do not have locking elements protruding from the outside, are known for example from WO0131386, EP632306 and EP2275647, wherein the end of the elastic element inside the housing is blocked by means of a tilting rigid body. The tilting body remains blocked in its seat inside the housing by means of an inclined bias produced by a coil spring. Thanks to the degree of freedom of the rigid tilting body, it is possible to intervene with a tool to rotate the rigid body backwards and hence freeing it from the engagement in its seat.
This solution is not completely secure, because the rigid body does not block naturally in its seat, but requires the collaboration and a correct alignment of the coil spring: if this cooperation of forces is not well calibrated, it is not possible to obtain a good assembly, or the disassembly is hardly achievable. Furthermore, the rigid body is not constrained to the carriage, therefore it requires specific production precautions to be handles by the eyeglass manufacturer.